FIELD OF THE INVENTION
The invention relates to the rolling of metal, and is concerned in particular with improvements in rolling mills for rolling various metal sections.
It is a particular problem to design a rolling mill which can be fitted with either relatively small rolls or relatively large rolls to suit the particular metal sections being worked and to drive the selected rolls at appropriate speeds and/or with sufficient torque.
It is also a problem in the design of rolling mills that, because of the need to roll at the highest possible rates of production, coupled with the fact that rolling loads within the roll stands are increasing, the driving of the rolls by means of universally jointed shafts is very often a limiting factor. This is because, although such shafts are capable of transmitting high torque when the driving shafts and rolls which they connect are in line, their torque transmitting capacity rapidly falls off when the rolls are moved out of alignment with the gearbox driving shafts, as of course they must often be when the roll gap is varied and even more so if the rolls are to be changed for different diameter rolls. Consequently, to reduce angularity, the universally jointed shafts in some cases need to be unduly long which results in a cumbersome (i.e. space consuming) arrangement and one which is not torsionally stiff.
The object of the invention is to provide a rolling mill which can be fitted with either relatively small rolls or relatively large rolls to suit the particular metal sections to be worked but which does not employ universally jointed shafts.
Another object of the invention is to solve the problem of how rolls of such widely varying diameters can be driven at appropriate speeds and/or with sufficient torque.
These and other objects and advantages of the invention are achieved by providing a rolling mill comprising a roll housing; a pair of cylindrical work rolls rotatable in said roll housing; a main frame and gear housing; respective drive gears located within said main frame and gear housing and in a first mode of operation of the mill drivably connected to said work rolls; respective pinions located within said main frame and gear housing and in constant mesh with the respective drive gears, said pinions in said first mode of operation of the mill meshing together and the respective drive gears being adjustable towards or away from each other, to suit the spacing of the rolls in the roll housing, by orbital adjustments of said drive gears around the respective pinions, mechanism whereby the main frame and gear housing can be located in either one of two positions angularly spaced at 180 degrees, and mechanism whereby the drive gears and pinions are capable of being re-adjusted in position within the main frame and gear housing so that for a second mode of operation of the mill the drive gears can be brought into mutually meshing positions and the pinions can be moved apart from their mutually meshing positions to become the gears with which the rolls are drivably connected, the pinions then being adjustable towards or away from each other, to suit the spacing of the rolls in the roll housing, by orbital adjustments of said pinions around the respective drive gears so that, depending upon the orientation of the main frame and gear housing and the adjustment of the gearing, there is obtained either a speed increase or a gearing down through the main gearbox, this providing a speed differential between the different roll drives obtained so that rolls of widely varying diameters can be driven at appropriate speeds.
Preferably, the drive gears and respective pinions with which they are in constant mesh will be located in respective cage members and so that for the first mode of operation of the mill the drive gears can be brought into mesh with each other and the pinions moved apart for orbital adjustment around their respective drive gears to suit the spacing of the rolls, and, when required, for the second mode of operation of the mill said pinions can be brought into mesh with each other and the drive gears moved apart for orbital adjustment around their respective pinions, again to suit the spacing of the rolls, said cage members preferably being secured for pivotal adjustment about the axes of the respective drive gears or of the respective pinions, selectively.
Preferably, also, means whereby either the pair of drive gears or the pair of pinions can be maintained in mesh, and the respective cage members secured for pivotal adjustment about the axes of the respective drive gears or of the respective pinions, selectively, include pairs of clamping plates pivotally movable about respective pivots and capable of being secured in alternative positions in which respective pairs of part-circular apertures selectively locate sleeve portions, concentric with the drive gears and pinions respectively, in respective part-circular seatings formed within the main frame and gear housing. The pairs of clamping plates may be movable about the respective pivots and secured in their alternative positions by means of a rotatable screw mechanism including a rotatable shaft with oppositely handed screwthreaded portions engaging respective nuts trunnion mounted between lever portions of the respective pairs of clamping plates, the shaft being adapted for rotation by an extraneous tommy-bar.
Means for effecting adjustments of the roll centres towards or away from each other preferably include pairs of eccentric sleeves located in bores in the roll housing, and compensating adjustment of the rolls to retain their axial alignment with the drive gears or with the pinions as the case may be will preferably be effected by re-adjustment of the roll housing in guides extending perpendicular to a plane containing the axes of the rolls. The main frame and gear housing will preferably have on its opposite end faces mounting means either one of which can receive the roll housing.
The main frame and gear housing will preferably be rotatably mounted for convenient positional adjustment into the selected one of its two angularly spaced positions. A hydraulically operated rotary actuator will preferably be provided to rotate the main frame and gear housing into the selected one of its two angularly spaced positions. The main frame and gear housing may be rotatable about a vertical axis for positional adjustment into the selected one of its two angularly spaced positions, the rolls of the roll housing being mounted for rotation about horizontal axes and being located at one end of the main frame and gear housing. Alternatively, the main frame and gear housing may be rotatable about a horizontal axis for positional adjustment into the selected one of its two angularly spaced positions, the rolls of the roll housing being mounted for rotation about vertical axes and being located above the main frame and gear housing.